hledger/Ledger/Amount.hs

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{-|
An 'Amount' is some quantity of money, shares, or anything else.
A simple amount is a commodity, quantity pair (where commodity can be anything):
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@
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$1
£-50
EUR 3.44
GOOG 500
1.5h
90apples
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0
@
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A mixed amount (not yet implemented) is one or more simple amounts:
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@
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$50, EUR 3, AAPL 500
16h, $13.55, oranges 6
@
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Commodities may be convertible or not. A mixed amount containing only
convertible commodities can be converted to a simple amount. Arithmetic
examples:
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@
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$1 - $5 = $-4
$1 + EUR 0.76 = $2
EUR0.76 + $1 = EUR 1.52
EUR0.76 - $1 = 0
($5, 2h) + $1 = ($6, 2h)
($50, EUR 3, AAPL 500) + ($13.55, oranges 6) = $67.51, AAPL 500, oranges 6
($50, EUR 3) * $-1 = $-53.96
($50, AAPL 500) * $-1 = error
@
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-}
module Ledger.Amount
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where
import qualified Data.Map as Map
import Ledger.Utils
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import Ledger.Types
import Ledger.Commodity
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instance Show Amount where show = showAmount
instance Show MixedAmount where show = showMixedAmount
instance Num Amount where
abs (Amount c q) = Amount c (abs q)
signum (Amount c q) = Amount c (signum q)
fromInteger i = Amount (comm "") (fromInteger i)
(+) = amountop (+)
(-) = amountop (-)
(*) = amountop (*)
instance Num MixedAmount where
fromInteger i = Mixed [Amount (comm "") (fromInteger i)]
negate (Mixed as) = Mixed $ map negate as
(+) (Mixed as) (Mixed bs) = normaliseMixedAmount $ Mixed $ filter (not . isZeroAmount) $ as ++ bs
(*) = error "programming error, mixed amounts do not support multiplication"
abs = error "programming error, mixed amounts do not support abs"
signum = error "programming error, mixed amounts do not support signum"
amounts :: MixedAmount -> [Amount]
amounts (Mixed as) = as
showMixedAmount :: MixedAmount -> String
showMixedAmount m = concat $ intersperse ", " $ map show as
where (Mixed as) = normaliseMixedAmount m
normaliseMixedAmount :: MixedAmount -> MixedAmount
normaliseMixedAmount (Mixed as) = Mixed $ map sum $ groupAmountsByCommodity as
groupAmountsByCommodity :: [Amount] -> [[Amount]]
groupAmountsByCommodity as = grouped
where
grouped = [filter (hassymbol s) as | s <- symbols]
hassymbol s a = s == (symbol $ commodity a)
symbols = sort $ nub $ map (symbol . commodity) as
-- | Get the string representation of an amount, based on its commodity's
-- display settings.
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showAmount :: Amount -> String
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showAmount (Amount (Commodity {symbol=sym,side=side,spaced=spaced,comma=comma,precision=p}) q)
| sym=="AUTO" = ""
| side==L = printf "%s%s%s" sym space quantity
| side==R = printf "%s%s%s" quantity space sym
where
space = if spaced then " " else ""
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quantity = commad $ printf ("%."++show p++"f") q
commad = if comma then punctuatethousands else id
-- | Add thousands-separating commas to a decimal number string
punctuatethousands :: String -> String
punctuatethousands s =
sign ++ (addcommas int) ++ frac
where
(sign,num) = break isDigit s
(int,frac) = break (=='.') num
addcommas = reverse . concat . intersperse "," . triples . reverse
triples [] = []
triples l = [take 3 l] ++ (triples $ drop 3 l)
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-- -- | Get the string representation of an amount, rounded, or showing just "0" if it's zero.
-- showAmountOrZero :: Amount -> String
-- showAmountOrZero a
-- | isZeroAmount a = "0"
-- | otherwise = showAmount a
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-- | Get the string representation of an amount, rounded, or showing just "0" if it's zero.
showMixedAmountOrZero :: MixedAmount -> String
showMixedAmountOrZero a
| isZeroMixedAmount a = "0"
| otherwise = showMixedAmount a
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-- | is this amount zero, when displayed with its given precision ?
isZeroAmount :: Amount -> Bool
isZeroAmount a@(Amount c _ ) = nonzerodigits == ""
where nonzerodigits = filter (`elem` "123456789") $ showAmount a
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isZeroMixedAmount :: MixedAmount -> Bool
isZeroMixedAmount = all isZeroAmount . amounts . normaliseMixedAmount
-- | Apply a binary arithmetic operator to two amounts, converting to the
-- second one's commodity and adopting the lowest precision. (Using the
-- second commodity means that folds (like sum [Amount]) will preserve the
-- commodity.)
amountop :: (Double -> Double -> Double) -> Amount -> Amount -> Amount
amountop op a@(Amount ac aq) b@(Amount bc bq) =
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Amount bc ((quantity $ convertAmountTo bc a) `op` bq)
-- | Convert an amount to the specified commodity using the appropriate
-- exchange rate.
convertAmountTo :: Commodity -> Amount -> Amount
convertAmountTo c2 (Amount c1 q) = Amount c2 (q * conversionRate c1 c2)
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nullamt :: MixedAmount
nullamt = Mixed []
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-- temporary value for partial entries
autoamt :: MixedAmount
autoamt = Mixed [Amount (Commodity {symbol="AUTO",side=L,spaced=False,comma=False,precision=0}) 0]